/**
 * Copyright (c) 2012-2016, www.tinygroup.org (luo_guo@icloud.com).
 *
 *  Licensed under the GPL, Version 3.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *       http://www.gnu.org/licenses/gpl.html
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.tinygroup.jspengine.util;

/**
 * Simple object pool. Based on ThreadPool and few other classes
 * <p>
 * The pool will ignore overflow and return null if empty.
 *
 * @author Gal Shachor
 * @author Costin
 */
public final class SimplePool {

    private static final int DEFAULT_SIZE = 16;

    /*
     * Where the threads are held.
     */
    private Object pool[];

    private int max;
    private int current = -1;

    private Object lock;

    public SimplePool() {
        this.max = DEFAULT_SIZE;
        this.pool = new Object[max];
        this.lock = new Object();
    }

    public SimplePool(int max) {
        this.max = max;
        this.pool = new Object[max];
        this.lock = new Object();
    }

    /**
     * Adds the given object to the pool, and does nothing if the pool is full
     */
    public void put(Object o) {
        synchronized (lock) {
            if (current < (max - 1)) {
                current += 1;
                pool[current] = o;
            }
        }
    }

    /**
     * Get an object from the pool, null if the pool is empty.
     */
    public Object get() {
        Object item = null;
        synchronized (lock) {
            if (current >= 0) {
                item = pool[current];
                current -= 1;
            }
        }
        return item;
    }

    /**
     * Return the size of the pool
     */
    public int getMax() {
        return max;
    }
}
